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Commit 97ba0c2b authored by Jan Kara's avatar Jan Kara Committed by Linus Torvalds
Browse files

mm: factor out common parts of write fault handling 

Currently we duplicate handling of shared write faults in
wp_page_reuse() and do_shared_fault().  Factor them out into a common
function.

Link: http://lkml.kernel.org/r/1479460644-25076-12-git-send-email-jack@suse.cz


Signed-off-by: default avatarJan Kara <jack@suse.cz>
Reviewed-by: default avatarRoss Zwisler <ross.zwisler@linux.intel.com>
Acked-by: default avatarKirill A. Shutemov <kirill.shutemov@linux.intel.com>
Cc: Dan Williams <dan.j.williams@intel.com>
Signed-off-by: default avatarAndrew Morton <akpm@linux-foundation.org>
Signed-off-by: default avatarLinus Torvalds <torvalds@linux-foundation.org>
parent b1aa812b

mm/memory.c

+37 −41
Original line number Diff line number Diff line
@@ -2062,6 +2062,41 @@ static int do_page_mkwrite(struct vm_area_struct *vma, struct page *page, 
	return ret;

}



/*

 * Handle dirtying of a page in shared file mapping on a write fault.

 *

 * The function expects the page to be locked and unlocks it.

 */

static void fault_dirty_shared_page(struct vm_area_struct *vma,

				    struct page *page)

{

	struct address_space *mapping;

	bool dirtied;

	bool page_mkwrite = vma->vm_ops && vma->vm_ops->page_mkwrite;



	dirtied = set_page_dirty(page);

	VM_BUG_ON_PAGE(PageAnon(page), page);

	/*

	 * Take a local copy of the address_space - page.mapping may be zeroed

	 * by truncate after unlock_page().   The address_space itself remains

	 * pinned by vma->vm_file's reference.  We rely on unlock_page()'s

	 * release semantics to prevent the compiler from undoing this copying.

	 */

	mapping = page_rmapping(page);

	unlock_page(page);



	if ((dirtied || page_mkwrite) && mapping) {

		/*

		 * Some device drivers do not set page.mapping

		 * but still dirty their pages

		 */

		balance_dirty_pages_ratelimited(mapping);

	}



	if (!page_mkwrite)

		file_update_time(vma->vm_file);

}



/*

 * Handle write page faults for pages that can be reused in the current vma

 *
@@ -2092,28 +2127,11 @@ static inline int wp_page_reuse(struct vm_fault *vmf, struct page *page, 
	pte_unmap_unlock(vmf->pte, vmf->ptl);



	if (dirty_shared) {

		struct address_space *mapping;

		int dirtied;



		if (!page_mkwrite)

			lock_page(page);



		dirtied = set_page_dirty(page);

		VM_BUG_ON_PAGE(PageAnon(page), page);

		mapping = page->mapping;

		unlock_page(page);

		fault_dirty_shared_page(vma, page);

		put_page(page);



		if ((dirtied || page_mkwrite) && mapping) {

			/*

			 * Some device drivers do not set page.mapping

			 * but still dirty their pages

			 */

			balance_dirty_pages_ratelimited(mapping);

		}



		if (!page_mkwrite)

			file_update_time(vma->vm_file);

	}



	return VM_FAULT_WRITE;
@@ -3294,8 +3312,6 @@ static int do_cow_fault(struct vm_fault *vmf) 
static int do_shared_fault(struct vm_fault *vmf)

{

	struct vm_area_struct *vma = vmf->vma;

	struct address_space *mapping;

	int dirtied = 0;

	int ret, tmp;



	ret = __do_fault(vmf);
@@ -3324,27 +3340,7 @@ static int do_shared_fault(struct vm_fault *vmf) 
		return ret;

	}



	if (set_page_dirty(vmf->page))

		dirtied = 1;

	/*

	 * Take a local copy of the address_space - page.mapping may be zeroed

	 * by truncate after unlock_page().   The address_space itself remains

	 * pinned by vma->vm_file's reference.  We rely on unlock_page()'s

	 * release semantics to prevent the compiler from undoing this copying.

	 */

	mapping = page_rmapping(vmf->page);

	unlock_page(vmf->page);

	if ((dirtied || vma->vm_ops->page_mkwrite) && mapping) {

		/*

		 * Some device drivers do not set page.mapping but still

		 * dirty their pages

		 */

		balance_dirty_pages_ratelimited(mapping);

	}



	if (!vma->vm_ops->page_mkwrite)

		file_update_time(vma->vm_file);



	fault_dirty_shared_page(vma, vmf->page);

	return ret;

}